Myanmar

PvDBPII of Myanmar P. vivax isolates displays a high level of genetic polymorphism and is under selective pressure.

The positive rates for blood stage antigens of P. falciparum were higher in Group I than in Group II, but the positive rates for antigens of other stages (PfLSA-1 and PfLSA-3) showed opposite results.

Using two polymorphic genetic markers, the merozoite surface protein genes PvMSP-3α and PvMSP-3β, we investigated the genetic diversity of four Southeast Asian P. vivax populations, representing both subtropical and temperate strains with dramatically divergent relapse patterns. PCR amplification of PvMSP-3α and PvMSP-3β genes detected three and four major size polymorphisms among the 235 infections examined, respectively, while restriction analysis detected 15 and 19 alleles, respectively.

We performed a molecular epidemiologic survey of mutations associated with drug-resistance genes in Plasmodium falciparum in northeastern Myanmar.

Although pharmacokinetic (ethnic-related) factors including resistance of P. falciparum to mefloquine contribute to some treatment failure following treatment with a three-day combination regimen of artesunate-mefloquine, results suggest that artesunate resistance may be emerging at the Thai-Myanmar border.

To determine the frequency of co-infections with Plasmodium species in southern Myanmar, we investigated the prevalence of P. knowlesi.

The proportion of the VK247 subtype in Myanmar was 43.1% (n=25) among 58 positive cases by serodiagnosis and 25.6% (n=24) among 94 positive cases by genetic diagnosis. In both diagnostic methods, the infection status of malaria patients is highly diverse with respect to malaria species, and multiple clonal infections are prevalent in Myanmar.

Extensive genetic polymorphism with diverse allele types was identified in MSP-1 and MSP-2 in P. falciparum field isolates from Myanmar. A high level of mixed infections was also observed, as was a high degree of multiplicity of infection.

These results have significant implications in understanding the nature of P. vivax population circulating in Myanmar as well as providing useful information for malaria vaccine development based on this antigen.

Microsatellite analysis is a useful tool for mapping short-term outbreaks of malaria and for predicting ancestry.